1. Technical Field
This invention relates to a drive train for an automatic focusing mechanism in a variable focal length camera in which a main lens system is moved forwardly and an auxiliary lens system provided behind the main lens system is allowed to go in and out of the photographic optical axis, in order to change the focal length. Focusing is achieved by moving the main lens only.
2. Description of the Prior Art
Japanese Patent Application Laid-Open No. 46610/1984, and others have disclosed a variable focus type camera which changes its focal length. It employs a mechanism in which a main lens driving system in the automatic focusing mechanism and the shutter are powered by a motor provided in a lens barrel unit which is movable back and forth. However, no consideration has been given to an integrated drive mechanism for the mechanical scanning involved in the distance measuring mechanism in the automatic focusing apparatus.
In the case of such a conventional variable focal length automatic focusing camera, the distance measuring mechanism is incorporated into the camera body. However, it is considerably difficult to electrically transmit to output signal of the distance measuring device to the lens barrel unit which is moving. Accordingly, in the case of a very popular manufactured unit, the distance measuring mechanism has a mechanical scanning mechanism, and its signal is mechanically transmitted to the main lens driving system. However, this mechanism is necessarily intricate, thus occupying a large part of the space in the camera. Obviously, this is unsuitable for making a compact camera.